A turbine for a gas turbine engine or a steam turbine engine may include a number of stages arranged along a longitudinal axis of the turbine. Each stage may include a rotor disk and a number of replaceable turbine blades arranged about an outer circumference of the rotor disk. To facilitate replacement thereof, the turbine blades may be removably attached to the rotor disk via dovetail connections by which root portions of the blades are inserted axially into respective grooves formed along the outer circumference of the rotor disk. Each groove of the rotor disk may have a dovetail shape having a “fir-tree” configuration that includes a number of slots and ribs, and the root portion of each turbine blade may have a mating dovetail shape and fir-tree configuration. In this manner, the root portions of the turbine blades may be retained radially within the respective grooves of the rotor disk during operation of the turbine.
Periodic cleaning may be carried out in order to remove contaminants from various portions of the turbine and ensure efficient turbine operation. For example, hardened dirt, oxidation residue, and/or other contaminants may accumulate within the grooves of the rotor disk during operation of the turbine over a period of time. In some instances, contaminants may pass through cooling air holes of the rotor disk and form sintered material within the grooves of the rotor disk due to the high turbine operating temperature. Cleaning of the rotor disk grooves may be tedious and time-consuming because each groove may include a number of different internal surfaces due to the fir-tree configuration, each rotor disk may include a large number of grooves, and access to the grooves by maintenance personnel may be limited. The rotor disk grooves generally may be cleaned prior to non-destructive testing, inspection, and general cleaning of the rotor, and the rotor may be on the critical path of the overall cleaning process. Accordingly, the amount of time spent cleaning the rotor disk grooves may directly impact the amount of downtime required for cleaning the overall gas turbine engine or steam turbine engine.
According to certain known cleaning methods, contaminants may be removed from the grooves of a rotor disk by hand, using a section of abrasive material to grind away contaminants from each desired surface of each groove. In view of the large number of surfaces, grooves, and rotor disks, such methods may require a substantial amount of time to complete the cleaning of a single turbine and thus may necessitate a long downtime of the turbine engine. Moreover, the quality and effectiveness of such cleaning methods may vary widely, as the degree of contaminant removal achieved may depend largely on the technique of the maintenance personnel carrying out the cleaning. According to other known methods, the rotor disk grooves may be cleaned by ice blasting, which uses compressed air and dry ice to remove contaminants from the grooves as well as other portions of the rotor disk. Such cleaning methods, however, may require expensive ice-blasting equipment and may be very noisy. Moreover, while ice blasting the grooves of a rotor disk, the process may prevent maintenance personnel from simultaneously cleaning or performing other work on other portions of the turbine rotor.
There is thus a desire for improved tools and methods for cleaning the grooves of a turbine rotor disc of a gas turbine engine or a steam turbine engine. Such tools and methods should allow maintenance personnel to quickly and efficiently remove contaminants from all desired surfaces of the rotor disk grooves. Additionally, such tools and methods should ensure that a substantially consistent degree of contaminant removal is achieved from one groove to another, even when the cleaning process is carried out by different maintenance personnel. Furthermore, such tools should be relatively inexpensive and easy to operate, and such methods should allow maintenance personnel to simultaneously clean or perform other work on other portions of the turbine rotor while the rotor disk grooves are being cleaned.